By the Chemtura AgroSolutions team of experts
You’d think that with the growing season winding down you could relax your guard against vineyard pests. But you’d be wrong.
Grape phylloxera is one more pest you must protect against. It’s a tiny aphid-like insect that feeds on Vitis vinifera grape roots, stunting growth of vines or killing them, and harvest and/or shortly thereafter is a good time to be on the lookout for this pest.
While this grape phylloxera prefers heavy clay soils that are found in the cooler grape-growing regions of the state such as Napa, Sonoma, Lake, Mendocino and Monterey counties, it’s also found in the Sacramento Delta and the foothills. Although the pest is present in the heavier soils of the San Joaquin Valley, damage may not be as severe, note experts with the University of California Integrated Pest Management team.
Initial infestations of grape phylloxera appear as a few weakened vines. These insects are difficult to detect in an apparently healthy vineyard. Therefore, monitor vines at harvest in an area of the vineyard that has consistently displayed weaker growth, especially vines at the edges of the weak areas.
Not unexpectedly, grape phylloxera infestations are more readily identified on vines growing in poor soils because their impact is greater on these vines than on vigorously growing ones.
If your vines are impacted by this pest, you’ll see that the infested area expands concentrically at a two- to fourfold rate a year. Satellite infestations frequently establish downwind from larger infested areas. When searching for phylloxera, be aware that populations die out on declining vines, warn IPM specialists.
• Concentrate on the periphery of declining areas where damage symptoms are still minimal.
• Dig near the trunk of vines under the drip emitter and look for whitish yellow, hooked feeder roots that are galled.
• Examine the galls with a hand lens for the presence of phylloxera.
Meanwhile, don’t forget to watch for mites, mealybugs and/or leafhoppers if you are still in harvest mode. Tools like Acramite® 50WS miticide, which delivers good knockdown mite control without affecting beneficials, is a key part of your arsenal. Acramite features a 14-day preharvest interval and a re-entry interval of only 12 hours, making it part of a good late season pest management program. Plus, its unique carbazate chemistry also makes Acramite an excellent rotational tool for resistance management.
Discuss late-season pest and weed management with your PCA or Chemtura AgroSolutions™ representative for additional ways to enhance your control program:
• Mike Ansolabehere, Southern San Joaquin Valley: (661) 304-3023; email Mike.Ansolabehere@Chemtura.com
• Matt Loftus, Central San Joaquin Valley: (559) 960-1112; email Matthew.Loftus@Chemtura.com
• Eric Leer, North Central California: (209) 531-6478; email